| Finally the homeowner can learn the little tricks of | | | | is cheaper than labor and that the best way to |
| the cleaning trade that the professional power | | | | assure return business is to do the best job that |
| washing contractors have been using for years to | | | | we can. |
| make their work look better, go faster and be | | | | The two types of chemical applicator pumps that |
| more cost efficient. | | | | are most commonly used in the mobile power |
| The application of chemicals is one of the longest | | | | wash industry are compressed air sprayers |
| standing controversies in the power washing | | | | {pump up style} and electrical diaphragm pumps. |
| industry. There are just as many opinions on the | | | | Pump up sprayers are often used because of |
| correct method of doing so as there are chemical | | | | budgetary reasons. The mobile power wash |
| applicators. The one thing most contractors seem | | | | industry is probably one of the least expensive |
| to agree on is that no single method will serve all | | | | fields of endeavor in which you can start and |
| circumstances efficiently. Of all the different | | | | successfully run a business. Therefore, you will |
| methods, the three most often used are 1) down | | | | find many people searching for cheap answers to |
| stream injection [after the pump], 2) chemical | | | | expensive problems. Mobile power wash |
| before the pump [through the pump], 3) and the | | | | contractors are on the whole some of the most |
| chemical applicator pumps. | | | | inventive people that you will ever meet. Pump up |
| Each of these methods has their benefits as well | | | | sprayers are an inexpensive answer to an |
| as their limitations. Down stream chemical injection | | | | expensive problem that they face regularly. |
| is most often used on cold pressure washers | | | | There are different styles and makes of these |
| because of low cost and the ability to turn the | | | | sprayers ranging in price from $ 14.00 to $ |
| chemical on and off at the wand. Chemical | | | | 145.00. The lower priced sprayers being the kind |
| injection before the pump is most often used on | | | | that you would find in a garden shop or hardware |
| hot pressure washers because of the ability to | | | | store that are designed for homeowner use. The |
| apply chemicals with hot water, which makes | | | | more expensive sprayers are of the type that |
| them more effective. And chemical application | | | | you might find at a contractor supply or a |
| pumps are used where the chemicals are not | | | | pressure washer distributor. Some of the |
| compatible with the pressure washer. | | | | differences would be better stronger construction, |
| The down stream injector is the most common | | | | viton seals and diaphragms, stainless steel |
| to the power wash industry. They are coupled | | | | corrosion resistant tanks or wetted parts and |
| in-line and operate on waterpower. The water | | | | epoxy coated steel. You will find all makes and |
| velocity is what creates the needed vacuum | | | | models in use in the industry but most often you |
| (venturi) to draw the chemical and mix it with the | | | | will find the medium priced sprayers being used |
| water flow. Changing the size of the discharge | | | | because they offer some longevity without the |
| orifice regulates the water velocity. This is most | | | | extreme expense. Some people won't use any |
| often accomplished using a roll over valve, a | | | | other type of sprayer because they really prefer |
| double nozzle head (see page 4), or a dual lance | | | | this method, but generally, they have chosen this |
| wand (see page 12). Most manufacturers of these | | | | method for economic reasons. Pumps up |
| injectors claim that their draw rates are from | | | | sprayers are available for spraying everything |
| 10% to 20%. With a few exceptions, I have | | | | from acid to deck sealer. Although repair parts |
| found this accurate. The problem with this is that | | | | are available for these types of sprayers in many |
| many people are requesting a draw rate in | | | | cases they are not worth rebuilding, depending |
| excess of 50%, which is only available with an | | | | upon the initial cost of the sprayer. When nothing |
| injector that is especially designed to fit at the | | | | else fits your budget, they can be quite useful. I |
| end of a spray lance (see page 13). The problems | | | | have used these types of sprayers and for small |
| with this injector are cost and due to the location, | | | | jobs they are tough to beat. You can be in and |
| it's a cumbersome package to handle for some | | | | out in less time than it takes to clean up a larger |
| applications. The contractors who most commonly | | | | more sophisticated unit. |
| request higher draw rates are ones who are | | | | The electrical pumps most often used are |
| applying chlorine to exterior surfaces such as | | | | self-priming, positive displacement pumps driven |
| buildings, decks, and fences. The reason for their | | | | by permanent magnet motors. They utilize a |
| concern is that the strongest concentrate of | | | | heavy-duty ball bearing/offset cam assembly, |
| sodium hypochlorite (chlorine) available is 15%. | | | | which drives a reciprocating two-piston plate. A |
| When this is mixed at a 10% to 20% ratio in the | | | | diaphragm is clamped between the inner and |
| injector, many people feel that it is too weak to | | | | outer pistons sealing the pumping chamber and |
| adequately clean and remove mildew. From this | | | | when actuated creates an alternating suction and |
| springs another question, the advisability of using | | | | pressure condition that opens and closes the inlet |
| chlorine as a cleaning agent to begin with. We | | | | and outlet check valves. They will have either an |
| could pursue this to infinity and never reach a | | | | internal bypass system or an on demand system. |
| consensus. | | | | These pumps are available in 12 volt DC and 120 |
| Another problem with this type of injector is due | | | | volt AC and 240 volt AC powered models. The |
| to the restriction created in the ¼" | | | | diaphragm that should be used for corrosive |
| pressure hose that is used as an integral part of a | | | | materials is made of viton because it is the most |
| telescoping wand. A down stream injector will not | | | | resistant to the type of chemicals used in the |
| work in most cases with a ¼" pressure | | | | mobile power wash industry. You will also need to |
| hose. This is because the ¼" hose creates | | | | use a valve assembly with viton parts. This will be |
| too much restriction and reduces the water flow | | | | incorporated in the new pump that you purchase |
| (increases the back pressure) causing the injector | | | | when you specify the use is for corrosives. |
| not to work. | | | | These pumps are available in different output |
| Other things that can inhibit the flow of water, | | | | volumes {expressed in gallons per minute}. These |
| thereby decreasing velocity and stopping the | | | | volumes will range from ½ to 6 gallons per |
| vacuum that is required to draw chemical, are: 1) | | | | minute. The size that one would choose would be |
| discharge hose in lengths of 200 feet or more, 2) | | | | directly related to the type of work that he is |
| installing the injector before the hose reel, water | | | | doing. Obviously if you were applying aluminum |
| heater, or other restrictive devices, 3) and using | | | | brightner to a truck you would not want to use a |
| certain types of trigger guns that are too | | | | 5 gpm pump. Nor would you want to use a |
| restrictive. | | | | ½ gpm pump to apply deck brightner when |
| One advantage of downstream injection is that | | | | preparing it to be sealed. |
| you will use less chemical. On the downside you | | | | In choosing, the appropriate pump for your |
| will clean slower because you will be applying the | | | | specific needs some of the things that you should |
| chemical under low pressure and rinsing on high | | | | consider is: the availability of electricity, the type |
| pressure. With up stream injection {before the | | | | of electricity available and the kind of chemicals to |
| pump} you will apply your soap as you are | | | | be applied. One of the more popular pumps used |
| washing on high pressure and rinse on high | | | | in the industry is the 12 volt model. This is |
| pressure as well. You will use more chemical this | | | | because even if you don't have a heavy duty |
| way but you will clean faster and more | | | | charging system on your pressure washer and a |
| thoroughly. Also down stream injector allows the | | | | large storage battery you probably do have some |
| operator to turn the chemical draw on and off | | | | sort of vehicle with a 12-volt charging system |
| from the gun whereas upstream chemical | | | | that you can attach it to. This means that you |
| injection [before the pump] requires that the | | | | can be totally self reliant without the added |
| operator return to the machine to turn the | | | | expense of a power generator. The 120-volt AC |
| chemical on and off. As you can see down | | | | model is more popular to the contractor who will |
| stream chemical injection can save many steps | | | | be working in areas where this type of power is |
| and a lot of time over the course of a day. | | | | readily available. Typically, you will find that these |
| Another major benefit down stream chemical | | | | units are being used in kitchen grease exhaust |
| application over before the pump injection is that | | | | cleaning, residential and industrial work where this |
| you can use chemicals that are corrosive in | | | | type of power is readily available. The 240 volt |
| nature (like acids) because they never enter the | | | | pump is seldom used, because this type of power |
| pump, unloader valve, or heater coils. | | | | is seldom found around a power wash job site. In |
| Upstream chemical injection is done by restricting | | | | my opinion that high of voltage would be |
| the inlet water to the pump. High-pressure pumps | | | | excessively dangerous. |
| used on hot high-pressure washers can pull a | | | | These pumps (most popular bands are Shurflo |
| vacuum. Therefore, these pumps do not have to | | | | and Flojet) will vary in price from $ 65.00 to |
| be pressure fed and they have the ability to draw | | | | $180.00 and are totally rebuildable. If you are |
| water and chemicals from water tanks and | | | | applying large amounts of chemical on a repetitive |
| chemical tanks. The vacuum is created with a | | | | basis, this is definitely a method to consider. You |
| restrictor barb or gate valves in the inlet plumbing | | | | can control the chemical mixture and the flow |
| to the pump. The operator has to return to the | | | | rate much better than most other ways of |
| pressure washer to turn the chemical on and off | | | | chemical application. |
| with a metering valve. These units have the | | | | Last but certainly not least is the application of |
| advantage in any strength of chemical can be | | | | chemicals through the use of foam generators |
| mixed with the inlet water. However, the chemical | | | | {foamers}. There are many different styles of |
| (usually a heavy duty alkaline detergent) must be | | | | foamers on the market today. They vary in price |
| compatible with the components in a pressure | | | | ranging from $50.00 to $900.00. The advantage in |
| washer. Most quality high-pressure washer | | | | applying chemicals using this method is that foam |
| detergents are compatible with the internal parts | | | | clings to vertical surfaces longer than less viscous |
| of a pressure washer (example: R-109 or | | | | liquids thus providing a greater dwell time for the |
| DNB-1430. | | | | chemical to work. |
| When considering the selection of injectors it is | | | | There are many other ways of applying the |
| important for you to understand how they work | | | | chemicals that are used in this industry. These are |
| and to determine their value to your style of | | | | the most commonly used methods. |
| cleaning. It is a well-established fact that chemical | | | | |